Former Massachusetts governor Mitt Romney, who has criticized Gingrich as an "unreliable" conservative who is too "zany" for the White House, largely stayed away from those kinds of attacks. He sought to play up his experience in the private sector, government and the Olympics as being ideal for challenging Obama on how to fix the economy.

USA TODAY's Susan Page and Jackie Kucinich will have more about the debate in Friday's editions. Highlights from our live blog are below:

10:54 p.m. ET

Huntsman points out he worked for Reagan. He calls for more trust in institutions and praises the level of debate among the GOP candidates.

10:52 p.m. ET

We're starting to wrap up and the topic is Ronald Reagan's 11th Commandment about not attacking people in your own party.

Gingrich says he's tried to talk about big ideas. "Any of these folks would be better than Barack Obama," he says. "Our only opponent is Barack Obama."

Paul suggests the "media is messing up" by not asking enough questions to flesh out the distinctions of the candidates.

10:48 p.m. ET

Gingrich is grimacing as Bachmann describes why she's stronger on abortion issues than him. She contends Gingrich supported Republicans in Congress who did not oppose certain late-term abortion procedures, which some critics call partial birth abortions.

He says her facts are wrong and she chides him for continually saying she's inaccurate. "My facts are accurate," Bachmann says. "I am a serious candidate for president."

Gingrich responds that when he was House speaker he said he would not "go out and purge Republicans" and says twice the chamber passed legislation to ban these procedures. The problem, he said, was Bill Clinton vetoed the bills.

10:43 p.m. ET

Santorum is taking exception with Romney's description of his record on social issues. He notes that Romney as Massachusetts governor issued gay marriage licenses and agreed with a court that upheld same-sex marriage.

"Very novel understanding of what our Supreme Court in Massachusetts did," Romney said as he disagreed with Santorum. He says the license issue wasn't up to him and he led an effort to pass a constitutional amendment defining marriage as between a man and woman.

10:40 p.m. ET

Romney is asked about his changing positions on abortion, gay rights and guns. He takes exception with including gay rights on the list. "I am firmly in support of people not being discriminated against based upon their sexual orientation," he says but stresses he is against same-sex marriage.

"Marriage is a relationship between a man and a woman," he says.

10:39 p.m. ET

Huntsman argues Obama has messed up the economy to the point where foreigners don't want to come to America anymore.

10:37 p.m. ET

Gingrich seems to echo Romney on the need for an E-Verify system. The disagreement, he says, is what to do about illegal immigrants who have been in the U.S. for a long time.

Gingrich says he'd drop the federal lawsuits against Alabama, Arizona and other states for their immigration laws and control the U.S.-Mexican border by 2014.

10:35 p.m. ET

Romney is asked about his past debate comment about sending illegal immigrants back to their home countries if they want legal status in the United States.

He calls for an identification card so employers can check the legal status of their workers. "Say to people here illegally ... you're not going to be able to work here," Romney says. "People who come here illegally ... should get in the back of the line."

10:32 p.m. ET

The topic is now immigration and border issues. The audience is applauding at the mention of Operation Fast and Furious, a failed gun-trafficking investigation. Perry says if Eric Holder was attorney general under him, then Holder should resign for Operation Fast and Furious. Santorum says he'd fire Holder if he was his attorney general.

10:26 p.m. ET

Perry is asked about favoring the oil and gas industry in Texas in the same way that Obama has helped Solyndra, the now-bankrupt solar energy company. Perry is defending his actions to help industries in Texas. "Government shouldn't be picking winners and losers," he says, explaining why he's not like Obama.

The Obama administration is under fire for providing Solyndra with more than $500 million in loan guarantees before the company went bankrupt.

10:25 p.m. ET

The subject is the Keystone XL pipeline from Canada to Texas and what should Congress do to get it built. Gingrich says he's been "editing" himself and is concerned about appearing to be "zany," the word Romney used against him yesterday.

Now he's blasting Obama for being "utterly irrational" on taxes, foreign policy and other issues. He says congressional Republicans should attach Keystone XL pipeline legislation to a middle-class tax cut and force Obama to veto it. The president has vowed to reject such a plan.

10:18 p.m. ET

Should there be military intervention in Syria? Perry says he's already called for a no-fly zone. He blasts the Obama administration for "absolutely bungling" foreign affairs.

10:16 p.m. ET

Would a Gingrich administration withdraw the United States from the United Nations? He says no, but he'd reduce the nation's reliance on the international body. "We have ... every obligation to tell the truth about how bad the U.N. bureaucracy is," he says.

Huntsman says the U.N. does valuable humanitarian and peace-keeping work, before he pivots to his view of foreign policy. His point: the U.S. has to fix its economy so it can be more effective overseas.

10:13 p.m. ET

"We need to only go to war with a declaration of war," Paul says as he turns to Bachmann.

She retorts, citing the International Atomic Energy Agency report that says Iran is on its way to building a nuclear weapon. Bachmann says "nothing could be more dangerous" than what Paul said. It's getting heated between Paul and Bachmann.

10:10 p.m. ET

On the day the Iraq war officially ended, the question: Are there circumstances where you'd send U.S. troops back into the country. Bachmann says Obama is "choosing intentionally to lose the peace."

She's going back to Iran and slamming Paul's answer to the previous questions. "We would be fools ... to ignore their purpose and their plan," she says about Iran.

Paul says he doesn't want Iran to have a nuclear weapon, and says it's wrong to say all Muslims are the same.

10:08 p.m. ET

The topic is now the U.S. drone that was brought down in Iran. Romney mocks Obama, saying the president said "pretty please" give the drone back.

10:07 p.m. ET

Santorum explains Iran has engaged in acts of war. "Iran is not like any other country ... they are a radical theocracy," he says. Mutual assured destruction, Santorum says, would not work. "It would be an inducement to war," he says, noting Iran wants to "create a calamity."

"They hate us because of who we are and what we believe in," Santorum says, advocating a strike against their facilities.

10:04 p.m. ET

Asked about sanctions on Iran, Paul says "all we're doing is promoting their desire to have" a weapon.

Foreign policy is the topic. "I fear another Iraq coming," Paul says about Iran's nuclear threat. He says the "greatest danger" is overreacting to Iran because "there's no evidence" that Iran has a weapon.

Santorum talks about how he challenged judges while he was in Congress. Perry says he doesn't want lifetime terms for federal judges.

9:54 p.m. ET

Romney is asked about passing over Republicans for the state bench in Massachusetts. He says to get his appointments through he had to appoint from both parties, and overwhelmingly appointed former prosecutors. Romney notes the possibility of the next president appointing several justices of the Supreme Court.

"We don't call it 'we the judges.' We call it 'we the people,' " he says.

9:53 p.m. ET

Would you abolish the 9th Circuit Court of Appeals? Bachmann says the real issue is whether the courts follow the Constitution. "The Congress and the President of the United States ... need to take back their authority," the congresswoman says, adding it's wrong to give the courts the right to make law.

Now she's hailing a Minnesota court ruling against gay marriage. She says she would only appoint federal judges who believe in the "original intent" of the Constitution.

9:48 p.m. ET

The topic now is the role of federal judges. "The courts have become grotesquely dictatorial," Gingrich says, pointing to a white paper on Newt.org about judges.

Then he says he'd be like Presidents Jefferson, Lincoln, Jackson and Franklin Roosevelt in challenging the judiciary. The history professor in Gingrich is coming out in full force.

9:46 p.m. ET

Romney is asked in what sectors will new jobs be created. "The free market will decide that," he says, as he slams Obama for the government's investment in Solyndra.

"Manufacturing is going to come back to the U.S.," he says, also touting energy and high-tech as "powerful" sectors.

9:45 p.m. ET

Santorum is asked about a tax holiday to bring back U.S. profits that have been made overseas. He says he'd have a 0% tax rate for companies who bring their profits back to America and invest on these shores.

9:43 p.m. ET

Huntsman is asked about the U.S. relationship with China. He suggests talking to dissidents who want to expand democracy in China. Over time it will create change, he says. "We share values in this relationship," Huntsman says, calling for "shared values" on human rights, greater tolerance for religion and democracy.

9:41 p.m. ET

Perry is asked about his record on keeping spending under control and a program he supported years ago when he was Texas agriculture commissioner. "Don't believe everything you read in the Austin American-Statesman," he says.

Now he's railing against Congress and his plan to cut members' pay and to make it a part-time institution. He wants Congress to meet 140 days every other year -- just like the Texas Legislature.

9:38 p.m. ET

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Paul is asked about his support for earmarks for his district. He turns the question around and says it should be explained that he doesn't vote for appropriations bills. Paul doesn't apologize for trying to get federal dollars back to his constituents.

9:36 p.m. ET

Gingrich is explaining his comment on Meet the Press criticizing a Medicare plan by Rep. Paul Ryan as "right wing social engineering." He and Romney praise a new bipartisan Medicare plan by Sen. Ron Wyden and Ryan.

9:34 p.m. ET

Gingrich hits back at Bachmann: "I have never once changed my positions because of any kind of payment," he says. "I was a national figure ... The fact is I only chose to work with people whose values I share" and he says it's important to help people buy their own home.

9:32 p.m. ET

Bachmann is asked about her claim that Gingrich engages in influence peddling. "We know he cashed paychecks from Freddie Mac." she says, slamming him for defending Freddie Mac and Fannie Mae.

"That's just not true," Gingrich shot back, saying he did no lobbying and talks about his efforts at housing reform. "People ought to have facts before they go out with allegations."

Bachmann says she's been backed by PolitiFact, the Tampa Bay Times fact-checking project.

9:30 p.m. ET

Paul says Gingrich has a different definition of free enterprise than he has. He says a GSE -- such as Freddie Mac -- is a government enterprise. Paul says the money comes from the taxpayer.

Gingrich responds that GSE has a "wide range" of meanings and there are a lot of good institutions that are government sponsored, like credit unions. "I did no lobbying for any kind for any organization," he says in reference to his Freddie Mac work.

9:29 p.m. ET

The topic is Gingrich's work for Freddie Mac. He's asked about a statement posted on the mortgage giant's website years ago in which he supports the company's business model.

"There are a lot of government-sponsored enterprises (GSE) that are awfully important and doing a good job," he says.

9:26 p.m. ET

Romney says Obama will level same attack on him about his work Bain Capital, as Gingrich did. Romney's been criticized for leading a venture capital company whose leveraged buyouts sometimes led to layoffs.

"I've learned from my successes and failures," Romney said. "We did our best to make those businesses succeed."

To create jobs it helps to have created jobs, he said.

9:25 p.m. ET

Iowa GOP Chairman Matt Strawn has a message to viewers and notes the state has had 33 straight months of voter registration gains.

9:20 p.m. ET

"Leadership is action, not words," Huntsman says, explaining how he ran on a flat tax proposal in Utah.

9:18 p.m. ET

Gingrich slams Obama as a "Saul Alinsky radical" as the candidates explain how they would make Congress and the White House work together. Then he talks about how he worked with Bill Clinton to get a tax cut.

9:15 p.m. ET

Jon Huntsman just explained why he's not doing better in the race. "I'm not going to contort myself into a pretzel," he says, repeating that he won't pander. Then he gets a little laughter by saying "I'm not going to Don Trump's debate."

9:13 p.m. ET

Rick Perry is asked about his poor debate performances and whether he could debate Barack Obama. He says he's getting to like debates and assures people he can do it. Then he drops a name that means something to the religious conservatives who vote in Iowa.

"I hope I am the Tim Tebow of the Iowa caucuses," Perry says about the Denver Broncos quarterback, whose faith is a big part of his game. The governor says Tebow had his doubters as well.

9:11 p.m. ET

Michele Bachmann is asked if she can appeal to independent voters. She says she's attracted Republicans and Democrats in her Minnesota campaigns. "I'm an action person," she says. "I spent five years going toe to toe with Barack Obama."

9:09 p.m. ET

Mitt Romney begins his answer about why he's better than Gingrich with a reminder of the country's economic problems.

"Government doesn't create jobs. The private sector does," he says. "I have credibility on the economy when he (Obama) doesn't."

9:08 p.m. ET

Why hasn't Rick Santorum caught fire? He says he's counting on the people of Iowa to light the match. The former Pennsylvania senator highlights his congressional record, and reminds people Gingrich was the subject of an attempted coup by his followers.

9:06 p.m. ET

Ron Paul gets laughs when he says anyone on the stage can beat President Obama. He says he's emphasizing civil liberties, monetary policy and the philosophy of freedom.

"I see this philosophy being very electable," the Texas congressman says, getting in that he wants to cut $1 trillion in federal spending his first year.

9:04 p.m. ET

Gingrich says he's got a 90% voting record with the American Conservative Union -- for 20 years. Now he's going through highlights of his House speakership, including tax cuts. It's "laughable" to say someone who's been with Ronald Reagan and Jack Kemp is not a reliable conservative, he says.

"My commitment to discipline ... is fairly obvious. People have to decide," Gingrich says, getting in that he doesn't change his positions.

Updated 9:03 p.m. ET

The first question from moderator Bret Baier is about electability.

Newt Gingrich starts by wishing everyone Merry Christmas. He reminds people electability was an issue with Ronald Reagan, too. "I believe I can debate Barack Obama," he says, asking for seven three-hour debates.

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About Catalina Camia

Catalina Camia leads the OnPolitics online community and has been at USA TODAY since 2005. She has been a reporter or editor covering politics and Congress for two decades, including stints at The Dallas Morning News and Congressional Quarterly. Follow her at @USATOnPolitics.